Infra-red generator



Nov. 27, 1956 H. A. MERRICK INFRA-RED GENERATOR Filed July 10, 1953mmvroza. Hermon A. Merrick BY Fig.7

United States Patent 2,772,336 INFRA-RED GENERATOR Herman A. Merrick,Seattle, Wasln, assignor, by mesne assi nments, to United Service 8;Utilities Co., Seattle, Wash, a corporation of Washington ApplicationJuly 10, 1953, Serial No. 367,227

1 Claim. (Cl. 201-63) This invention relates to infra-red generators ofthe type disclosed in United States Patent No. 2,535,268, issuedDecember 26, 1950, and namely, a generator comprising an electricallyenergized coil of filament wire encased in a glass tube. The coil ispeculiarized in that the convolutions of the coil are coated with ajacketing cement permitting the coil, while operating under a conditionof high heat transmittal, to safely contact the glass wall of thecontainer without any liability of either the coil failing or the glassdisintegrating due to the heat of the coil. In this generator heat wavesof two frequencies are created, high-frequency waves emanating from thecoated coil and low-frequency waves from the tube. These waves are heldto a predetermined constant throughout the length of the generator andwill operate to distribute the radiated heat such as to givesubstantially uniform penetration throughout the entire area to whichthe heat is directed.

In the aforesaid patent the ends of the glass tube are annealed andclosed with stainless steel caps which are internally coated with asealing cement. The ends of these caps have central openings so that thecaps can be fed over the projecting terminals of the coil and onto theannealed ends of the tube. These terminals are then secured to the capsby solder which also serves to seal the openings in the latter. Thisarrangement requires that the caps be socketed in electricallyconductive clips, such as copper fuse clips, thus making a far moreexpensive installation than would be found if the ends of the coil couldhave a wire interconnection with the power leads to the heating unit inwhich the tube is mounted.

Accordingly, it is a principal object of the present invention toprovide an inexpensive arrangement whereby the ends of the glass tubesare sealed without requiring a modification of such ends and whichpermits the terminals of the energized coil to be easily connected towire extensions. In carrying out this object, the invention further aimsto electrically insulate the coil at the ends of the tube and to providemeans whereby the generator can be supported at its ends withoutdirectly contacting the glass of the tube.

Other more particular objects and advantages will appear and beunderstood in the course of the following description and claims, theinvention consisting in the novel construction and in the adaptation andcombination of parts hereinafter described and claimed.

In the accompanying drawings:

Figure 1 is a fragmentary plan view of an uncoated coil with the wireleads attached.

Fig. 2 illustrates the step of dipping the coil into a bath of a cementcoating material.

Fig. 3 shows the manner in which the coating on the coil is dried.

Fig. 4 is a side view of one of my novel end plugs.

Fig. 5 is a front end view of the plug.

Fig. 6 is a side view of a completely assembled generator unit.

Fig. 7 is a fragmentary view of an end portion of 2,772,336 PatentedNov. 27, 1956 the generator assembly and with the respective end plugbeing shown in vertical section taken longitudinally through the centerof the plug.

In forming the energizing coil 10 for the generator, the ends thereofare formed with terminal hooks 11. Over these hooks are looped therespective ends of nickel wire extensions 12, 13, silver solder 14 beingused to make permanent connections. These wire leads have asbestosinsulating jacets 15. As disclosed in the aforesaid patent, the wire ofthe coil 10 is desirably Nichrome and is insulated with a jacket ofcement such, for example, as Sauereisen cement mixed with magnesiumoxide in the approximate proportion of 2 to 1. To apply this cementjacket the assembly of Fig. 1 is manually grasped by the asbestosjackets 15 and dipped into a bath 16 of the coating as illustrated inFig. 2. The free ends of the wire extensions 12, 13 are then bridgedacross live terminals 17, 18 (Fig. 3) to pass current through the coiland thereby heat the same until the coating is dry.

Continuing to the other figures in the drawing, it is seen that I employround plugs 20 to close the ends of the Pyrex glass tube 21 of uniformdiameter in which the filament coil is to be housed. These plugs arestepped to provide a capping section 22, having a diameter correspondingto the outside diameter of the tube 21, and a shorter plugging section23 having a diameter slightly less than the inside diameter of the tube.Each plug has a central through-bore 24 and its outer face is radiallygrooved from this bore as at 25 to a depth exceeding the outer diameterof the asbestos jacket-s 15. The material for the end plugs is desirablyceramic or glass so as to be electrical insulators and not susceptibleto breakage due to high temperatures.

In assemblying my improved infra-red generator the coated filament coil10 with the attached asbestos-jacketed wire extensions 12, 13 is placedin the tube 21 with the said sections extending therebeyond. Cement 26which is not subject to deterioration from high temperature conditions,such as, for example, Sauereisen Insalute Adhesive Cement #1 Paste, isapplied to the plugs 20 along the underside of each capping section 22and the circumferential side face of each plugging section 23. The plugsare then slipped over the wire extensions 12, 13 to seat the pluggingsections in the ends of the tube where they are permanently held by thecement 26 as best shown in Fig. 7.

After the plugs are thus seated, the wire extensions 12, 13, which areat this time extending lengthwise out through the plug bores 24, arebent at right angles to the longitudinal axis of the tube so that theycan be seated in the radial grooves by an application of cement 27 whichmay be the same type as the cement 26 used to bond the plugs to thetube. The cement 27 also covers the mouth of the bores 24 so that thetube is sealed.

The resulting final assembly is shown in Fig. 6 and it will be seen thatit can be readily installed in dryers, food warmers, heaters, etc. bysocketing the exposed capping sections of the plugs 20 in simple clips,desirably thermally insulated, and connecting the free ends of the wireextensions 12, 13 to power leads. Since the plugs 20 are electricallynon-conductive, and the asbestos insulating jackets 15 for theextensions 12, 13 are thermal resistant, the clips holding thegenertor'do not have to be electrically insulated. The Nichrome Wire isapplicable to the normal operating temperatures below 2,000 F. Wire ofother material as, say, tungsten, is necessarily used in those instanceswhere higher operating temperatures are required.

The invention admits to minor changes in the details of construction andit is my invention that the hereto annexed claim be given a scopecommensurate with the 3 broadest interpretation which the employedlanguage fairly'perrn'itsi What I claim is:

An infra-red generator comprising a glass tube, cerarn'ic terminal plugsextending by. necked-down portions into "said tube and having enlargedheads without the tube; said plugs each having a longitudinal bore and agroove in the outer end face of its enlarged head' extending laterallyfrom'the said bore to the'si'de extremity of the head, a wire coilassembly in the tube and'having extensions passing endwise through thesaid bores and seated in the said grooves, said extensions havingasbestO S j 'dkf; fiid" (:eiii'ei'if 'lioifdliig"theplugs" to the tube,holding the jacketed extensions in the grooves, and sealing the saidbores in the plugs.

References Cited in the file of this patent UNITED STATES PATENTS1,525,331 Steineret'a'lf Feb. 10, 1925 10 v2,42%,021 Henklerretialr June24, 1947 2,535,268" Coats 1360.26, 1950

